Toll trunk-circuit



0. F. CASSAD AY. TOLL TRUNK CIRCUIT. APPLICATION FILET) mac. 6. 1915.

Patented Apr. 13, 1920.

2 SHEETS-SHEET I.

ZZEUEZYZEI'J Erma-1270 I 555 fia.

ww qaqw 0. F. CASSADAY., TOLL TRUNK'CIRCUIT.

APPLICATION FILED DEC. 6, 1915.

2 SHEETS-SHEET 2.

Patented Apr. 13, 1920.

2' 2755525. 51/527757?! 4 -W" UgUZYiFESSE iiy. M wfiagk J 5.272% g.

UNITED STATES PATENT OFFICE.

ORMOND F. CASSADAY, OF CHICAGO, ILLINOIS, ASSIGNOR T0 KELLOGG SWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO,

ILLINOIS, A CORPORATION OF ILLINOIS.

TOLL TRUNK-CIRCUIT.

Specification of Letters Patent.

atcnted Apr. 13, 1920.

Application filed December 6, 1915. Serial No. 65,216.

To all whom it may concern Be it known that'I, ORMOND F. CassanAY, a citizen of the United States of America, residing in Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Toll Trunk- Circuits, of which the following is a specification.

My invention relates to trunk circuits for telephone systems for use in extending connections from one exchange to another and has to do more particularly with so-called toll trunk circuits, an object of my invention being to provide an improved system of the above character.

The general practice in handling so-called toll calls is to have an operator commonly known as an A-operator answer the inc0ming calls by means of an operators cord circuit and then to extend the calling subscribers line to a so-called toll operators board, upon which appears-one end of all the toll trunks leading to the toll boards in the dis tant cities. The toll operator then extends the connection over the toll trunk to the toll operators board at the distant city. The toll operator at the distant city then extends the toll call to a local operator who completes the connection with the desired called-for subscriber. It has been found necessary to extend all toll calls through a distant toll operator's board instead of directto a local operator-s board as a great many of the toll connections handled by the toll operator must be extended through the toll operator's board. over a second toll trunk. to another toll operators board in a third city. Systems of the above described character have been found faulty owing to the length of time that is consumed by the toll operator at the incoming end of the toll trunk in connecting to an idle local operator and for the local operator to then extend the connection to the desired called subscriber. T0 overcome this objection, I provide a parallel branch circuit connecting the toll trunk to a local operators board and provide means at the outgoing end of the trunk by which the toll operator may either signal the local operator at the opposite end of the trunk if a local connection in that city is desired, or she may signal the toll operator in the same place and she then extends the toll call over a. second toll trunk to a third toll operators board. By this method the incoming toll calls are operator direct doing away with the time required for the toll operator to extend the connection from her position to a local operator. I also provide means by which'the toll operator may control the connection of the local operators telephone set with the toll trunk whereby she may immediately inform the local operator that a toll connection is desired. At the same time means is provided for designating to the local operator the trunk over which the tollconnection is being extended and for causing a busy lamp to be lighted upon the toll operators board to show that this trunk is being used and that it is not accessible to her for extending a connection back to the originating toll operators board. There are other features of my invention and these will be more particularly referred to in the following specification and the appended of trunking handled by a local 7 claims.

Referring more in detail to my invention as illustrated in the accompanying drawings, in Figure 1, I show a calling substation A, an operators link circuit B for connecting to the line of the calling subscriber for extending a connection either to a local subscriber or to the toll trunk circuit D. The outgoing end of the toll trunk circuit D terminates upon the local operators board or upon a toll operators board in a trunk jack TJ. In the case in which the trunk circuit D terminates upon a toll operators board, an operators trunk circuit (not shown) is used by the local operator for extending the connection from the calling line to the toll operators board. The toll operator then extends the connection through the trunk jack TJ to the trunk circuit D. The opposite end of the trunk circuit D terminates upon a distant local 0 )erator's board in a trunk calling plug TCT and upon the toll operators board in a jack J. The local operator connects either direct to the called subscribers line through the medium of the multiple jack J (Fig. 2) or connects through the medium of a trunk jack T3 to an automatic switch F (Fig. 2), that is then operated to extend the call to the called subscribers line.

The calling substation A is of a wellknown common battery type terminating at the exchange in a line circuit L comprising a line relay LR, a cut-ofl' relay CO, multiple jacks J and a line signal S.

The local operators cord circuit B comprises an answering plug AP and a calling plu CP connected by the heavily marked conductors. At the answering end of the cord. circuit B, I provide answering tip and sleeve supervisory relays AT and AS, the

two relays controlling a supervisory sig-' nal SS. At the calling, end I provide calling tip and sleeve supefrvisory relays CT and OS, the two relays controlling a supervisory signal SS A listening key LK is shown which when moved to its alternate position connects an operators set O to the cord conductors and a ringing key RK is provided which when actuated connects a ringing generator GE to the strands of the calling plug OP. The calling plug OP may be inserted into the multiple jacks of a called line or if a call be. for a subscriber at a distant exchange, the said plug CP may be used to connect to the outgoing end of a toll circuit C.

The outgoing end of the toll circuit C terminates in a trunk jack TJ and an orderwire key OW is provided which when moved to its alternate position brings about circuit changes in the trunk circuit D, as will be hereinafter more fully described. A drop signal'DS is provided for denoting incoming calls and a relay CO and a supervisory signal SS for supervisory purposes. A repeating coil RC is shown comprising the windings 1, 2, 3, 4, a condenser K being interposed between the windings 1 and 2. The trunk conductors 5, 6 lead to a test panel at the distant exchange and terminate in a jack JA. A patching cord PC is shown which connects the jack JA through the jack JA to the conductors 5 and 6 which lead therefrom to the trunk circuit D and terminate in windings 7, 8, of a repeating coil RC The repeating coil RC of the trunk circuit D comprises the windings 7, 8, 9 and 10, said trunk circuit D terminating in a trunk calling plug TOP upon a local operators board. A trunk jack J which terminates upon a toll operators board is connected through the medium of the jacks JA and J A and patching cord'PC to the trunk circuit D. An operating relay OR is provided which is operated-upon the depression of the key OW, to close a circuit through the operators connecting relay ON.

The said relay CN upon ene rgizing connects the operators set O to the conductors of the trunk circuit D. The relay ON also operates to. close a circuit for the disconnect lamp DL. The glowing of this lamp identifies the particular trunk that is being used by the originating'toll operator in extending the connection to the local operator at trunk circuit D. 'A busy relay BB is also provided which energizes upon the operat1on pf the relay OR and operates to mechanically look its armature in an attracted position. The relays OB, ON and BB restore when the orderwire key OW is released but the armature of relay BR- remains in its alternate position due to it being mechanically locked, the armature remalnmg in its alternate position which keeps the trunk bus lamp TL of the toll circuit glowing. X trunk sleeve relay TS 1s provided which is operated when the operator inserts the trunk plug TOP into the ack of a called line but when the said plug s inserted into a trunk jack leading to an 1dle connector switch the relay TS does not operate until the called line contacts have been seized and the side switch has assumed its second position. The relay TS, upon energizing, establishes a circuit for relay 11, which relay upon energizing closes a circuit for the cut-off relay C0 of the toll circuit E at the toll operators board. A release magnet BL is provided which operates to restore the locked armature of relay BR and to close a circuit for the ringing control relay RC.. The relay RC, upon energizing closes an energizing circuit for the relay 12 and the cut-ofi relay C0 of the trunk C lighting the supervisory signal SS notifying the local operator at cord circuit B that the connection has been extended to the called subscriber. The local operator at B is provided with a ringing key BK which when actuated connects the ringing generator G to the trunk circuit D to operate the ringing control relay BC. The operation of relay RC closes a circuit for the disconnect magnet DR and ringing relay RI, the said relay RI connects ringing current from V the proper frequency generator GE, GE GE or GE due to the depression of the ringing key plunger of the ringing key BK to the line of the called subscriber. A trunk ti relay TT is provided which is operated w en the calledsubscriber answers and brings about certain circuit changes in the trunk circuit D, as will be more fully hereinafter described. A test relay TR and a normall energized relay 15 are provided for testing the idle or busy condition of a called line; I show a calling device CD which may be connected to the tip conductor of the trunk circuit D upon the operation of the connecting key OK and is used for controlling an automatic connector switch F as illustrated in Fig. 2 when connection is to be extended to an automatic exchange to call a subscriber Whose telephone termlnates at said automatic exchange. The calling device is illustrated diagrammatically but the dial used in the system illustrated is adapted to transmit a plurality of impulses, say from 1 to 50. The toll trunk circuit E terminates in a jack J as hereinbefore mentioned. Associated with the jack J is a drop D8 a cutoff relay CO and a supervisory lamp TL. Conductors 203 and 204 connect the trunk conductors of circuit D to the jack JA located at the test panel and a patching cord PO connects the jack J A with a jack J A and the conductors 205 and jack J A to the trunk jack J If the patching cord PC and PC be withdrawn from the connected jacks JA, JA and JA JA direct connection is established between one exchange and another by direct toll line without going through the auxiliary apparatus at the local operators board.

In Fig. 2 I show a called common battery substation G terminating in a line circuit L comprising the usual line relay LR cutoff relay (0 multiple jacks J and line signal 5 The connector swing lF is of the well-known type and terminates at one end in a trunk TJ before a trunk operator and at its other end at the automatic exchange in Wipers 16, 17 and 18. The subscribers lines terminate in back contacts 19, 20 and 21 accessible to the wipers 16, 17 and 18 of connector switch F. The connector switch F as shown is preferably a one-motion switch, that is it has rotary motion only, the said switch being provided with the usual switch shaft, (not shown) which carries the wipers 16, 17, and 18. I also show the side switches a, Z). 0, and (Z, which assume their second position when contacts of the called line have been seized by the wipers of connector switch F. A primary relay PR and primary magnet PM supply motor power to step wipers 16, 17 and 18 over the bank contacts 19, 20, 21 into engagement with the contacts of the called line in response to the impulses which are transmitted from the calling device CD. A side switch relay SlV is provided to control the said side switch wipers in a well-known manner. A release magnet RM and a side switch release magnet SM are also provided which control the release of the wipers 16. 1'7, 18 of connector switch and also the said side switches a. 7), c, and (I. A busy back tone BB is provided which operates when a busy line is encountered to notify the calling subscriber and also the trunk operator. of the busy condition of the called line. ()it normal contacts ON are also associated with the connector switch F and assume their alternate position upon the first step of the wipers 16, 17 and 18 off normal. I show a called ai tomatic substation H provided with the usual apparatus also including a calling device CD Substation H terminates in automatic equipment I, which includes a line relay LR and a cut-off relay CO Having described in general the apparatus embodying my invention, I will now de- 206 connect the I operation of my system =='the listening key LK tozconnect her operators set to the cord conductors. The insertion of the answering plug AP into the jack J establishes a series energizing circuit for the answering sleeve supervisory relay AS and the cutoff relay CO. The energization of the said relay (30 opens the circuit of relay LR- bringing about the ef facement of the signal S. The answering tip supervisory relay AT also operates from battery through relay AS through the now closed contacts of the relay CO, through the substation and back through the winding of said relay AT to ground. The operation of the two supervisory relays AT and AS prevents the premature lighting of the supervisory signal SS. The operator having connected her operators set 0 to the cord conductors now inquires the wants of the calling subscriber. and assuming that it is the subscriber at the common battery substation G, which subscriber is located at a distant exchange. the operator now inserts the calling plug (P in an idle jack TJ ot' the toll circuit and depresses the orderwire key ()VV to connect a local operator's set at the distant exchange to the conductors of the trunk circuit I). after which she operates ringing key BK to connect the ringing generator (ill to bring about circuit changes in the trunk circuit D which will be more fully described in the ensuing specification. The operator at link circuit B instead of connecting direct to the trunk jack TJ,'II13. V connect to a trunk extending to toll operators board. the toll operator would then extend the connection to the trunk circuit D. For illustrative purposes. I have. shown the connection extending direct from a local operators circuit to the toll trunk circuit. The insertion of the plug into the trunk jack TJ closes a circuit for the relay CS from battery through the winding of relay CS, sleeve contacts of the plug and jack through the impedance coil IC to ground. The relay (S operating brings about the closing of alternate contact 200 to close the continuity of the tip conductor of link circuit B. The closing of the alternate contact 22 of the orderwire key OW' establishes an energizing circuit for the relay OR of the trunk circuit D at the distant local operators board, from. battery through the resistance R. alternate contact alternate contact 28'of relay OR. ,The closure of alternate contacts 30 and 31 of relay CN connects the trunk operators set 0 to the trunk conductors. The operator at the outgoing end of the trunk now informs the local operator at the trunk circuit D the connection desired. The closure of alternate contact 28 of relay OR also establishes an energizing circuit for relay BR from battery through the winding of relay BR, conductor 29, to round at alternate contact 28 of the relay contact 32 of relay BR closes a circuit for the trunk busy lamp TL, traced from battery through the alternate contact 32 of relay BR, conductor 33, through the busy lamp TL to ground causing the said lamp to glow, thus notifying the toll operator associated with the toll circuit E that the trunk D is in use. contact 34 of relay CN establishes a circuit for the disconnect 'lamp DL of the trunk D, traced from battery through the said lamp, conductor 35, normal contact 36 of relay 12 to ground at alternate contact 34 of relay CN, lighting the said lamp, identifyin the particular trunk that is being used y the trunk operator for completing the connection. The local operator at the incoming end of the trunk now tests the wanted line as to its idle or busy condition in the usual manner, and if the wanted line is busy, the sleeve of the multiple jack of the wanted line will be of a potential above that of ground, bringing about the operation of relay TR over a circuit tracedfrom battery at the sleeve of the busy jack through the tip of the plug TOP, normal contact 37 of relay RI, normal contact 38 of relay TS, normal contact 39 of the dial connecting key (1K and through the winding of relay TR to ground. The closure of alternate contact 40 of relay TR places ground from the normal contact 41 of relay TS through the alternate contact 40 of relay TR, the alternate contact 42 of relay 15 (which is normally held energized,

through contacts 40 and 41 of relay TR and TS to ground) test conductor 43 to the tertiary winding of the operators induction coil to battery, roducing the usual click in the operators ead receiver. When testing an idle line the relay TR remains normal R. The closure of alternate The closure of alternate due to the jack associated with the idle line being at a ground potential and no click is received. I

Assuming that the line being called is idle, the o erator now inserts the trunk calling plug CP into the multiple jack J of the called line and depresses one of the plungers of the ringing key RK to select the proper generator frequency to ring the call bell of the subscriber at the called substation G.

The local operator having released the orderwire key OW after repeating the wanted number to the trunk operator brings about the restoration of the relay OR by openin its circuit at connector 22 of the key 0 The relay OR restoring to normal brings about the deenergization of re lays CN and BB, the relay ON restoring again opens its contacts 30 and 31 disconnecting the operators set the relayBR although it has its energizing circuit interrupted does not assume its normal position due to the said contact 32 being mechanically locked in its alternate posltion. The said contact 32 remaining closed keeps the trunk bus lamp TL lighted indicating the busy con ition of its associated trunk circuit. The insertion of the plug TOP into the jack J of the wanted line establishes a series energizing circuit for the cut-off relay C0 of line circuit L and the relay TS of trunk circuit D, traced from battery through the upper winding of relay TS, sleeve contacts of the connected plug and jack through the windin of the relay CO to ground. The relay T upon energizing closes alternate contact 41 thereby establishin an energizing circuit for relay 11, tracef from battery through the windings of the relay 11, the make before break contact 44 and conductor 45 to ground at alternate contact 41. Relay 11, upon energizing closes its alternate contact 46 thereby establishin an energizing circuit for the cutofl re ay C0 of the toll circuit E. The circuit for cut-off relay CO extending from battery through the Winding of the relay CO and over conductor 47, to und at alternate contact 46 of relay 11. Rela CO upon energizing disconnects drop D 1 and closes asecond circuit for the lamp TL.

The closure of the alternate contact '41 of the relay TS also establishes an energizing circuit for relay RL, traced from battery through the winding of the relay RL, conductors 48, 49 and normal contact 50 of relalyl TT to ound at alternate contact 41. T e relay R upon energizing brings about the restoration of the spring 32 of the relay BR due to its mechanical relation with the armature of relay BR, opening the initial circuit of the lamp TL, but a substitute circuit for the said lamp TL was previously closed at alternate contact 51 of relay CO. The relay RL, upon energizing, removes the short circuit about the ringing control relay RC due to the normal contacts 25 and 26 assuming their alternate position while the closing of alternate contacts 25 and 26 establishes a series circuit for the relay 12 of the trunk D and cut-ofl relay C0 of the toll circuit C, traced from battery through both windings of the relay 12 in parallel. alternate contacts 25, 26, windings 7 and H of repeating coil RC, trunk conductors 5 and 6, to point 24, then over conductor 23. through normal contact 22 of the key OW, alternate contact 53 of the trunk jack 'lJ and through the Winding of the relay (Y to ground. The closing of alternate contact 54 of relay CO closes a circuit for the lamp SS traced from battery through the lamp SS to the alternate contact 54 of relay CO to ground- The lighting of the said lamp SS notifies the operator at the outgoing end of the trunk circuit D that the call has been extended to the called subscriber and that the subscriber may now be rung. The operator at the cord circuit B now throws the ringing key RK to connect the generator GE across the trunk conductors thereby causing the operation of the relay RC over a circuit traced from the ungrounded pole of the generator GE, alternate contact 55 of the key RK, the tip contacts of the connected plug andjack. winding 1 of relay RC, condenser K, winding 2 of the re peating coil RC, sleeve contacts of the con nected plug and jack to battery and ground through alternate contact 57 ofthe key RK. The ringing current is repeated into the windings 3, 4 of repeating coil RC. thence over conductors 5 and 6 and windings 7 and 8 of the repeating coil RC causing relay RC to be energized. Relay RC, upon energizing, closes its alternate contact 58 bringing about the energization of the relays DR and RI. The circuit for relay DR extends from battery through the winding of relay DR, alternate contact 59 of the relay 11, conductor 60. alternate contact 58 of relay RC'and over conductor 61 to ground at alternate contact 62 of the relay 12. The relay 11 is held energized due to the make before break contact 44 of relay DR over a circuit traced from battery through the winding of the relay 11. the make-beforebreak contacts 44 of relay DR, conductor 63. conductor 60, alternate contact 58 of relay RC and conductor 61 to ground at alternate contact 62 of relay 12. Relay RI is also energized at the same time over a circuit traced from battery through the winding of the relay RI. conductor 60, alternate contact 58 of relay RC and conductor 61 to ground at alternate contact 62 of relay 12. Upon the closure of alternate contact 37 of relay RI. ringing lead 64 is connected to the tip side of the trunk circuit D which connects the proper generator frequency to the called line according to the button operated upon the party line ringing key RK. The ringing circuit of the called line extends from the connected generator GE, which we will assume is the generator selected over ringing conductor (54, alternate contact 37, tip contacts oi" the connected plug and jack, through condenser and call bell of the called substation back through the sleeve contacts of the jack and plug, through alternate contact 55 of relay ltl to battery and round. The operator at the cord cir cuit controls the ringing of the called subscriber and each time the key RK is thrown circuit changes are brought about as above described to ring the call bell of the called subscriber. ltelay DR operating opens its normal contacts 66 and 67 interrupting the trunk conductors to prevent interference from the repeated ring. Ground from alternate contact 62 over conductor 61, through alternate contact 58, over conductor 60 through the now closed contact 68 of relay 15 through the lower winding of relay TS to battery, prevents the relay TS from being deenergized during the ringing period.

Upon the removal of the receiver at the called substation G, the circuit for relay TT is established, traced from battery through the upper winding of the relay TS, sleeve contacts of the connected plug and jack, closed contacts of the switclrhook, back through the tip contacts of the connected plug and jack. normal contact 37 of relay RI, alternate contact 38 of relay TS and through the winding of relay T T to ground. The opening of normal contact 50 of relay TT upon its energization, opens the circuit for the relay RL and also opens the circuit of lamp DL at a second point. BL upon deenergizing, opens the energizing circuit of the relay 12 at normal contacts 25 and 26. The restoration of the re- The relay lay RL also allows the cut-oil relay C0 of the toll circuit C to restore opening its alternate contact 54 eflacing the signal SS thus notifying the operator at cord circuit B that the called subscriber has answered. The calling and called subscriber at substation G may now carry on conversation over the heavily marked conductors.

Assuming now that the subscribers have finished conversation, the replacement of the receiver at called substation G brings about the restoration of relay TT. The said relay TT, upon deenergizing. closes its normal contact 50 closing the circuit of relay BL,

which again energizes to close a. series energizing circuit for relay 12 and the cut-oil relay C0 The said relay CO again energizing, closes its alternate contact 54 to light the signal SS The lighted signal SS notifies the operator that the called subscriber subscriber at the substation A 115 has replaced his receiver and she now withbr" about the lig ting of supervisory signal S. The operator not' the hghted s' l withdraws om ack J.

' contact 41 of rela gilug AP T e withdrawal 0 the plug CP from the jack TJ opens the circuit for the relay 12, which relay, upon its restoratlon -closes a circuit for the disconnect lam DL. .The circuit for the lamp DL exten from battery through the said lamp, conductor 35,-

normal contact 36 of relay 12, conductor 70, normal contact 34 of relay ON, conductor 49, and normal contact 50 of relay TT to und at alternate contact 42 of relay TS.

he lighting of the lamp DL notifies theoperat'or of the trunk circuit D that the subscribers have finished conversation and that the local operator has withdrawn the plug from the trunk i'ack TJ. She now removes the trunk plug CP from the 'ack J opening the circuit of the relay S, which relay, upon its restoration opens the circuit of relay RL. The opening of the alternate TS also eflaces the disconnect signal D The apparatus of the cord circuit B and trunk circuit D are now at normal and are-available for establishing other connections. Assuming now'that the subscriber at the ca substation A, wishes to converse with the su riber H whose telephone terminates at an automatic exchange, the operation of this connection is the same up to the time that the operator of the trunk circuit D inserts the plug TOP into the trunk jack TJ connected to an idle connector switch as F at the automatic exchange. -The operator first tests the trunk circuit which leads to a connector as F, in the manner as'above described, and assuming that the trunk tested,

leads to an idle connector, the operator then inserts the plug TOP into the trunk jack \TJ and depresses one of the key plungers of the ringing key to select the pro r enerator frequency to ring the call hzll at the called substation. The insertion of the plug into the trunkjack closes a series ener 'z-' ing circuit for the relay TR of the trun D and primary relay PR of the connector switch F, traced from batte through the winding of the said relay P contact 73, wiper 74 of the side switch 6, tip contacts of the connected plug and jack, normal contact 37, normal contact 38, conductor 75, normal contact 39 of the dial connecting key CK through the winding of the relay TR to ground. Relay TR, upon energizing opens its contact 40, therebyopening the circult of the normally energizedrelay 15 allowing the said relay to dener ze. The said relay 15, upon denergizing, c oses its normal contact 42 thereby establishing a circuit for the disconnect lamp DL, traced from battery through the said lamp, normal contact 42, conductor 76, alternate contact 40 of relay TR, and conductor 77 to ground at normal contact 41. Assuming that the called subscribers number is 38, the operator now presses the dial connecting ke DK to connect the calling device CD to't e tip conductor of the line and then operates the calling device in a well-known manner to transmit 38 impulses tooperate the connector switch F to select the contacts of the called line and the impulses transmitted due to the closing and o ening of contact 72 of the calling device C are transmitted from battery throu h .the winding of the primary relay PR 0 conductor switch F, contact 73, wiper 74 of side switch I), tip contacts of the connected plug and jack, normal contact 37 normal contact 38, alternate contact 39 o ke DK, to ground at alternate contact 72.

lpon the ,first energization of the relay PR, an energizing circuit for the slow acting relay 78 is established extending from. battery through the windin of relay 78 to ground at alternate contact %9 of relay PR. The closing of alternate contact 80 of relay 78 establishes an energizing circuit for the relays 81, 82, the circuit for relay 81 being traced from battery through the winding of relay 81, conductor 83 to ground at alternate contact 80, the circuit for relay 82 being traced from battery through the winding of the said relay conductor 84, side switch wiper 85, contact 86 to ground at alternate contact 80 of relay 7 8. Upon the first decnergization of relay PR, an energizing circuit for primary magnet PM is established from battery through the wind-' ing of magnet PM, conductor 87, alternate contact 88 of relay 78 to ground at normal contact 79 of relay PR. Relay 78 being slow to release its armature, its contact 81 is held in its alternate position during the transmission of impulses to the primary magnet PM. The impulses from the calling device CD as before described, cause the primary relay PR toenergize and denergize due to the closing and opening of contact 72 of the dial CD. The said magnet PM is likewise energized and denergized due to the opening and closing of contact 79 of relay PR, the said magnet PM stepping wipers 16, 17 and 18 of the connector switch F into engagement with contacts 19, 20 and 21 of the called line. The relay 78 as before described, being slow acting, is not affected by the rapid interruptions of the relay PR and therefore the relays 81 and 82 remain energized durin the transmission of impulses. Upon t e first step of the wipers ofl normal; the off-normal contacts ON assume their alternate position. The impulses having ceased the relay PR remains de- Lnergized thereby opening the energizing circuit for the relay 78, said relay restoring and opening the circuits for relays 81 and 82- at contact 80. The relay 78, upon deenergizing closes a circuit for side switch magnet SW from battery through the winding of said relay SW, conductor 90, alternate contact 91 of the off-normal contacts ON, contact 92 and Wiper 93 of the side switch a to ground at normal contact 94 of relay 78. Upon the energization of the magnet SW, the side switch wipers 7 1, 85, 93 and 95 are stepped into their second position into engagement with contacts 97, 99, 96 and 98. When the side switch wiper 93 leaves its contact 92 and en ages contact 96, the circuit for the magnet W is opened, the said magnet deenergizing permits side switches a, b, c, and d to remain in their second position. As soon as the side switches have assumed their second position a series circuit for the relay 100 and the relay TS of the trunk circuit D is established, said series circuit being traced from ground through upper winding of relay 100, conductor 101, contact 98, wiper 95 of side switch 0, sleeve contacts of the connected plug and jack, conductor 102, through the upper winding or relay TS to battery. The closing of alternate contact 11 of relay TS brings about the operation of the relay RL, which relay upon energizing opens contacts 25and 26 removing the short circuit about relay RC. The closing of alternate contacts 25 and 26 closes the series energizing circuit for relay 12 and cut-off relay (0 at the toll circuit C. The energization of the said cut-off relay (0 brings about the lighting of the signal SS said signal notifying the operator at the cord circuit B that the call has been extended to the called substation. The local operator now throws her ringing key RK and brings about the energization of the relay RC which relay, upon energizing closes a circuit for the relays DI and RI as already described. The energization of the relay RI connects ringing lead 64 to the tip of the trunk circuit D. The path for the ringing current extends from the ungrounded pole of the generator GE through closed contacts of the plunger of the ringing key RK, ringing lead 64:, alternate contact 37 of relay RI, tip contacts of the connected plug and jack, wiper 74, contact 97, normal contact 104 of relay 81, wiper 17, contact 20, condenser and call bell at the substation G, contact 21, wiper 18, normal contact 105, to contact point 105 where the current divides, part of it going through normal contact 107 of relay 108, through winding of the relay 109 to battery, part extending through the condenser K, contact 98, through the upper winding of the relay 100 to ground and part extending through the wiper 95 of the side switch 0, sleeve contacts of the connected plug and jack, conductor 110 and through the alternate contact to battery and ground. Each time the operator at the local cord circuit B operates the ringlng key RK, the relay RC is energized bringlng about circuit changes as above descr bed, to energize relay R1 to connect ringing current to ring the call bell of the called subscriber.

\Vhen the subscriber at called substation H answers in response to his call bell. the t1p trunk relay TT of the trunk circuit 1). and relay 109 of connector switch F are energized in series. the said energizing circuit being traced from ground through the winding of said relay TT. of trunk circuit I), alternate contact 38 of relay TS, normal contact 37 of relay RI, tip contact of the connected plug and jack, wiper 71, contact 97, contact 111 of relay 109, normal contact 104 of relay 81, wiper 17, contact 20 through the now closed contacts of the switch hook through the substation H contact 31, contact 18, normal contact 85 of relay 81, normal contact 107 through winding of relay 109 to battery. Upon the energization of the relay TT of the trunk circuit 1), the energizing circuit for the relay BL is interrupted at the normal contact 50 of the said relay TT. The relay RL restoring opens the series energizing circuit for the relay 12 and the relay ("0 which latter relay, upon restoring. opens the circuit of the supervisory signal SS at contact 54 efl'acing the said signal and notifying the operator at cord circuit B that the called subscriber has answered. l'pon the energization of the relay 109, a circuit for relay 108 is closed, traced from battery through the lower winding of relay 108, alternate contact 112 of relay 109, normal contact 105') of relay 81, wiper 18 of contact 21 through the closed contacts of switch-hook H, contact 20, wiper 17, normal contact 104 of relay 81, the alternate contact 113 of relay 109 through the upper winding of the relay 108, to ground. The relay 108 furnishes battery for talking purposes to the called subscribers telephone. The relay 108. upon energizing, closes a substitute circuit for the relay 109, said substitute circuit being traced from battery through the winding of said relay 89, alternate contact 107 and through the winding of relay 114 to ground. The relay 114 upon energizing, opens the release circuit for the connector switch F at a second point and prevents the connector switch from releasing until the called subscriber has replaced his receiver upon the switchhook and the operator has removed the plug from the trunk jack which leads to the connector switch F. The energization of the relay 108 also closes a substitute circuit for the relay TT of the trunk circuit D extending from ground through the winding of relay TT, alternate contact 38, normal contact 37, tip contacts of the connected plug and jack, wiper 74, contact 97, con ductor 115, normal contact 116 of relay 108 and through the lower winding of relay 100 to battery. The subscribers are now in conversational circuit. The said talking circuit may be traced over the heavily marked conductors.

Assuming now that the subscribers have finished conversation, they replace their receivers upon their respective switchhooks. The replacin of the receiver at the called substation opens the energizing circuit for relay 108, which relay restores and opens the energizing circuit for relays 114 and 109 at contacts 107 of relay 108. The tip relay TT of the-trunk circuit D is also denergized due to the replacing of the receiver at the called substation H. The normal contact 50 of relay TT is again closed establishing a circuit for the relay RL which again closes its alternate contacts 25 and 26 to establish the series energizing circuit for relay 12 and cut-ofi relay CO. The relay C0 upon energizing, again lights supervisory signal SS to notify the operator at cord circuit B that the subscriber at the called substation has replaced his receiver. The circuit for the release magnet RM and the said switch release magnet SM is not as yet closed due to the fact that the relay 100 is still held energized from'battery through the trunk sleeve relay TS at the trunk circuit D. The operator at the cord circuit B noting the lighted signal SS removes plug P from trunk jack TJ opening the series circuit of the cut-0H relay CO and relay 12 of trunk circuit D. Relay 12 upon deenergizinlgl, closes a circuit for the disconnect lamp D said circuit being traced from battery through the said lamp, conductor 35, normal contact 36, conductor 70, normal contact 34, normal contact 50 through alternate contact 41 to ground. The operator 'at trunk circuit D noting the lighted lamp DL removes the trunk calling plug T from the trunk jack TJ The removal of the plug from the said trunk jack opens the circuit'of relay 100, which relay deenergizes and closes the circuits of the release ma net RM and side switch release magnet SM? The circuit of release magnet RM extends from battery through the winding of said magnet RM, conductor 316, alternate contact 117 of off-normal contacts ON, normal contact 118 of relay 82, normal contact 119 of relay 114 to ground at normal contact 120 of relay 100. The circuit for magnet SM extends from battery through the winding of the said magnet, conductor 116 following the same path as that of magnet RM. The magnet RM, upon energizing, releases the wipers 16, 17, and 18 allowing them to restore to normal and the magnet SM, upon energizing, releases the side switch to normal or first position. The ofi-normal contacts ON are also restored to normal thus opening the circuit of magnet RM and side switch magnet SM. The two magnets operate to restore to normal the apparatus of connector F. Upon the removal of the jack TCP from the trunk jack TJ the circuit for the relay TS of trunk circuit D is opened brin ing about the deenergization of the relays L and 11. The apparatus of the trunk circuit D is now at normal and is available for establishing other connections. The operator at the cord circuit B receives the disconnect signal from the calling subscriber A in a well-known manner, whereupon she removes the answering plug AP from jack J thereby restoring the apparatus of the cord circuit B to normal.

Now, assuming that the called automatic subscribers line is busy, the operation of the circuit is the same as previously described up to and including the time that the side switch is stepped to second position to engage the contacts 96, 97, 98 and 99. The called subscribers line being busy, a ground will be encountered by the private wiper 16 when it engages the private contact 19, the said ground being furnished by another switch already in connection therewith. The

relay PR deelnergizes as before after the group of impulses have been transmitted and opens the contact 79 bringing about the restoration of the relay 78. The side switch relay SR is energized as before through the normal contact 9-1 of relay 78 to ground, the relay SlV stepping the side switches a, b, a and d into their second or final position. The side switch wiper 85 having stepped to its second or final position opens the energizing circuit for the slow acting relay 82. The relay 81 has its circuit interrupted due to the opening of the contact 80 of relay 78. The relay 81 also being slow acting, a substitute circuit for the said relay is established before it restores. The said circuit extends from battery through the winding of the relay 81, conductor 83, normal contact 80 of relay 78, conductor 130, alternate contact 131 of said relay 81, conductor 132, conductor 133 to the ground encountered by the private wiper 16. The side switch relay SW is therefore held energized, the circuit being traced from battery through the winding of the said relay, conductor 90, alternate contact 91, and alternate contact 135 to round at normal contact 136 of relay 82.

he relay 100 is energized as soon as the side switch has moved to its second position, the circuit extending from ground through the upper winding of the relay 100, contact 98, wiper of side switch, sleexe contacts of the connected plug and jack through the upper winding of the relay TS of the trunk circuit D to battery. Upon energization of the relay 100 the tone generator T0 is started, its circuit being traced from battery through the tone generator TU, alternate contact 137 to ground at alternate contact 120 of relay 100. The busy back machine is now connected to the trunk circuit D over a circuit traced from battery through the busy back BB, alternate contact 138, of relay SW, alternate contact 104 of relay 81, makebefore-break contact 111 of relay 109, contact 97, wiper 74, tip contacts of the connected plug and jack, normal contact 37 of relay RI, alternate contact 38 ofrelay TS through the winding of relay TT to ground. The busy signal is also transmitted to the calling subscriber notifying him that the called line is busy. The relay TT of the trunk circuit D is thus intermittenly operated due to the busy back machine. The intermittent operation of the relay TT causes the relay RL to energize and denergize which in turn opens and closes the series circuit for relay 12 and cut-off relay C0 of the trunk circuit D and toll circuit C which brings about the flashing of the su pervisory signal SS The operator noting the flashing of supervisory signal SS knows that the called line is busy and removes plug CP from jack TJ. This removal of the plug GP from jack TJ causes signal DL to be operated. The operator at D noting the glowing of the disconnect signal DL removes the plug TCP from the jack TJ which opens the energizing circuit of relay 100 which relay upon deenergizing closes release circuit for magnet RM and side switch relay SM as above described. The two relays upon energizing, bring about the restoration of wipers 16, 17 and 18 of connector switch F and side switches a, b, c and d. The restoration of the other connected apparatus is the same as above described.

It will now be assumed that the calling subscriber at substation A desires a toll connection which necessitates the use of the toll circuit E at the toll board in the distant exchange. The operator at cord circuit B after receiving the calling subscribers instructions in the same manner as hereinbefore described, inserts the calling plug (JP into the trunk jack TJ of the toll trunk circuit B and operates the ringing key RK to bridge generator G across the tip and sleeve conductors of the cord circuit B. The bridging of the generator GE across the windings 1, 2 of the repeating coil RC causes current to be induced in the coils 3 and 4 of the repeating coil RC, which is transmitted over the trunk conductors 5 and 6 and through the coils 7 and 8 of the repeating coil RC at the distant end of the trunk circuit D. The windings 7 and 8 of repeating coil RC operate to induce current in the drop DS the windings 9 and 10 of said repeating coil thus current is transmitted over the conductors 205 and 206 through the drop signal DS located on the toll operators board. The toll: operator-noting the 1 operation of inserts the answering plug of a link circuit (not shown) into the jack J connected to the toll circuit E. The insertion of the answering plug into the jack J 4 causes contacts 217 to be closed thereby closing a circuit through the cut-ofl' relay ()0 of toll circuit E and through the disconnect relay DR of the trunk circuit D at the local operators board. The disconnect relay DR upon energizing, disconnects the tip and sleeve conductors of the tip calling plug TCP from the windings 9 and 10 of the repeating coil RC Cut-off relay CO upon energizing, disconnects the drop DS from across the conductors 205 and 206 of the toll circuit E and closes a circuit through the supervisory lamp TL. The toll operator now inquires of the operator at the outgoing end of the trunk circuit D the connection desired and after receiving this information extends the connection in the direction of the called subscribers line.

Now assuming that the toll operator at circuit E wishes to extend a connection back to a subscriber located in the first exchange, she inserts the calling end of a link circuit (not shown) into the jack J and operates the ringing key of said link circult to connect ringing current across the conductors 205 and 206 of the circuit E. The insertion of the plug into jack J 4 brings about 'the operation of the cut-olf relay C0 of circuit E and the disconnect relay DR of trunk circuit D at the local operator 5 board in the same manner as hereinbefore described. The bridging of the ringing current generator across the conductors 205 and 206 causes the operation of the drop signal DS associated with the trunk jack TJ at the toll operators board at the distant end of the trunk circuit. The distant toll operator inserts the answering plug of the link circuit into the trunk jack TJ and receives instructions from the toll operator of toll circuit E. She then extends the connection in the direction of the called sub, scribers line.

From the foregoing it is seen that I have provided a two-way circuit extending between two toll operators boards which has a branch extending to a local operators board, thus forming a Y-shaped trunking circuit over which a connection may be extended in either direction from one toll board to the other and over which a connection may be extended from the one toll operators board to a local operators board, thus making possible rapid fire service in one direction over the trunk circuit without going through the toll operators board at the incoming end of the trunk circuit. When it is ,desired to use the toll circuit as a direct toll circuit between the toll operators boards, the patching cords PC and PC may be removed thus disconnecting the local operators equipment and making a throu h toll trunk over which connection may be extended in either direction.

While I have described my invention in connection with a certain circuit arrange- .ment, I do not wish to be limited to the same as my invention is applicable to other circuit arrangements and many changes and modifications will readily suggest themselves to those skilled in the art, therefore I do not wish to be limited to the exact arrangement as shown, but aim to cover all such changes and modifications as come within the spirit and scope of the appended claims.

Having described my invention, what I claim as new and desire to secure by United States Letters Patent, is: 1. In a telephone system, subscribers telephone lines, a trunk circuit for extending connections from one exchange to another exchange, a link circuit for connecting one of said subscribers lines to said trunk circuit, a trunk operators telephone, and means controlled over the two sides of the trunk circuit in parallel for automatically connecting said operators telephone with said trunk circuit.

2. In a telephone system the combination of a link circuit connected to a trunk circuit, a trunk operators telephone, automatic means for connecting the trunk operators telephone with the trunk circuit, and means controllable by the link circuit operator for operating the said automatic means, said last means comprising a circuit including the two sides of the trunk circuit in parallel.

3. In a telephone system, a trunk circuit for extending connections from one exchange to another exchange, a trunk operators telephone, and means controlled over the two sides of the trunk circuit in parallel for automatically connecting said operators telephone with said trunk circuit, and a supervisory signal for said trunk circuit controlled over the two sides of said trunk circuit in parallel.

4. In a telephone system, a trunk circuit for extending connections from one ex change to another exchange, a supervisory signal for said trunk circuit located at one of said exchanges and controllable over the two sides of the trunk limbs in parallel, and automatic means for operating said signal continuously or intermittently.

5. In a telephone system, a trunk circuit having its opposite ends terminating at different operators boards, a supervisory device associated wlth one end of sald trunk circuit, means associated with the opposite end of said trunk circuit for operating said supervisory device over the two sides of said trunk circuit in parallel, and automatic means for intermittently operating said last means to cause said supervisory device to be intermittently operated.

6. In a telephone system, an operators link circuit, a trunk circuit adapted to be connected to said link circuit, a trunk operators telephonefor connection to said trunk circuit, means for connecting said operators telephone to said trunk circuit, and means controllable by the link operator for operating said connecting means over the two sides of the trunk circuit in parallel.

7. In a telephone system, an operators link circuit, a'trunk circuit adapted to be.

connected to said link circuit, a trunk operators telephone for connection to said trunk circuit, means for connecting said operators telephone to said trunk circuit, and means controllable by the link operator for operating said connecting means over the two sides of the trunk circuit in parallel whereby said trunk operators telephone is operatively connected to the link operators telephone.

8. In a telephone system, a calling and a called subscribers line, a trunk circuit, means for connecting said calling line to said trunk circuit, means for connecting the said trunk circuit to the called subscribers line, a supervisory device associated with one end of said trunk circuit, and means as sociated with the opposite end of said trunk circuit and controllable by said called subscriher for closing an operating circuit for said supervisory device including the two sides of said trunk circuit in parallel.

9. A telephone system comprising subscribers telephone lines, a trunk circuit for interconnecting said lines, one end of said trunk circuit appearing upon a trunking operators board and the opposite end of said trunk circuit having parallel branches appearing upon different operators boards, a signal for each parallel branch of said trunk circuit, and means controllable by the trunking operator for operating either of said signals independently of the other.

10. A telephone system comprising subscribers lines, a trunk circuit for interconnecting said lines, one end of said trunk circuit terminating upon a trunking operators board and the opposite end of said trunk circuit being divided into two parallel branches which appear upon a trunking operators board and a local operators board, a signal for each parallel branch of said trunk circuit, and means controlled by the said first trunking operator for operating either of said signals.

11. A telephone system comprising sub scribers lines, a trunk circuit for use in interconnecting said lines, one end of said trunk circuit terminating upon a trunking operators board and the opposite end of said trunk circuit being divided into parallel branches which appear upon different operators boards, a signal for each of said parallel branches, means controlled by the trunking operator over the two sides of the trunk circuit in parallel for operating one of said signals, and means controlled over the two sides of the trunk circuit in series for operating the other of said signals.

12. In a telephone system, a trunk c1rcu1t terminating at one end upon a trunking operators board and at its opposite end upon a local and upon a second trunking operators board, a calling signal at the local operators board, a supervisory signal at the second trunking operators board, means controllable over the two sides of the trunk circuit in series for operating said calling signal, and means for operating said supervisory signal when said trunk circuit is taken for use.

13. In a telephone system, a calling and a called subscribers line, a trunk circuit, means for connecting the calling subscribers line to the trunk circuit, parallel branch circuits for the opposite end of said trunk circuit, calling signals for said parallel branches, means controlled over said trunk circuit for operating either of said calling signals independently of the other, and means for completing the connection to the called subscribers line.

14. In a telephone system, a calling subscribers line, a called manual and a called automatic subscribers line, a trunk circuit, means for connecting the calling subscribers line to said trunk circuit, and means for connecting the opposite end of said trunk circuit to either said called manual or automatic subscribers line, a supervisory signal at one end of said trunk circuit, and means controlled over the two sides of said trunk circuit in parallel when the connection is extended to either of said called lines for operating said supervisory signal. 7

15. In a telephone system, the combination of a calling subscribers line connected to a trunk circuit, a supervisory signal associated with one end of said trunk circuit, means for connecting the opposite end of said trunk circuit directly to a called manual subscribers line or to a called automatic subscribers line, and means for operating said supervisory signal over the two limbs of said trunk circuit in parallel.

16. In a telephone system, a trunk circuit having its one end terminating upon a trunking operators board and its opposite end terminating upon a local operators board, means controlled by the trunking operator line,

over the two sides of the trunk circuit in parallel for operatively connecting the local operators telephone to the trunk circuit, and means controlled by the local operator for extending a connection to either a manual or an automatic subscribers line.

17. In a. telephone system, a trunk circuit terminating at one end upon a trunking operators board and having its opposite end divided into parallel branch circuits terminating upon different operators boards, a calling signal for said trunk located upon one of said last boards, a supervisory signal for said trunk located upon another of said last boards, and means for operating said calling signal to denote a call and for operating said supervisory signal to show that said trunk is in use.

18. In a telephone system, a trunk circuit terminating at one end upon a trunk operators board and at its opposite end upon a second trunking operators board and upon a local operators board, cut-ofl relays 'for said trunk, and means controlled by the operator at said first trunking board for signaling for connection over one of said branches and for operating the cut-off relay of the other of said branches.

19. A telephone system including an operators link circuit provided with a manual connection terminal, a telephone set, and means controlled over the two sides of the circuit in parallel for connecting said telephone set to said link circuit.

20. A telephone system including subscribers telephone lines, a link circuit for connecting said lines, a supervisory lamp for said link circuit, and automatic means controlled over the two sides of said link circuit in parallel for intermittently flashing said supervisory lamp.

21. A telephone system including a link circuit, a signal for said link circuit controllable over the two sides of said link circuit in parallel, and automatic means responsive to the connection of said link circuit to a busy called line for intermittently operating said signal.

22. A telephone system including a link circuit, a trunk circuit adapted to be connected to said link circuit, an operators telephone for connection to said trunk circuit, and means controllable by the link circuit operator over the two sides of the trunk circuit in parallel for connecting said operators telephone to said trunk circuit.

23. A telephone system including a calling subscribers line and a called subscribers line, a link circuit, means for connecting said link circuit to the calling subscribers a supervisory device for said link circuit, and meansassociated with one end of said link circuit to operate said device over the two sides of the link circuit in parallel when said called subscriber responds or for intermittently operating said supervisory device When said link circuit is connected to a busy called subscribers line.

24. A telephone system including a calling subscribers line, a. link circuit for connection to said calling subscribers line, a supervisory device for said link circuit, means for connecting the opposite end of said link circuit directly to a called manual subscribers line or to a called automatic subscribers line, and means controlled over either of said latter lines for operating said supervisory device over the two limbs of said link circuit in parallel.

25. A telephone system including a connecting circuit, a pair of signals individual to and associated with one end of said circult, and means for operating one of said.

signals over two sides of said circuit in series and for operating the other of said signals over the two sides of said circuit in multiple.

26. A telephone system including subscribers telephone lines, a link circuit, means for connecting said link circuit to a subscribers telephone line, a signal an operators telephone, and means controlled over the two sides of said link circuit in multiple for controlling said signal or said operators telephone.

27. A telephone system including a connecting circuit, a signal for said connecting circuit, an operators telephone, means controlled over the two sides of the link circuit in parallel for connecting said operators telephone thereto, and means controlled over the two sides of said circuit in parallel for operating said signal.

28. A telephone system including subscribers telephone lines. a link circuit for use in connecting said lines terminating at its one end in an A. operators board and at its opposite end intwo different ll operators boards, a signal for each of said latter branches of said circuit, and. means for operatingeither ot-said signals independently of the other.

29. A telephone system including subscribers telephone lines, a connecting circuit for interconnecting said lines, said connecting circuit terminating at its one end in an A operators board and at its opposite end in a pair of B operators boards, cut-off relays for said circuits at each of said latter boards, and means for operating either of said cut-ofi' relays independently of the other.

30. A telephone system including subscribers telephone lines, a connecting circuit for interconnecting said lines, said connecting circuit terminating at its one end in two branch circuits, signals for said branch circuits, and means controlled over the said connecting circuit for operating either of said lamp signals independently of the other.

Signed by me at Chicago in the county of Cook and State of Illinois, in the presence of two Witnesses.

ORMOND F. CASSADAY. lVitnesses Gr. A. YANOCKOWSKT, B. OBRIEN. 

